In an attempt to provide containers having gas barrier properties, various multilayer structures have been developed according to the intended use of the containers. A multilayer structure having gas barrier properties generally includes a base and a gas barrier coating formed on the base. This multilayer structure is used as a packaging material constituting a container. The container is fabricated, for example, by subjecting the multilayer structure in the form of a sheet to a joining process and thus forming it into a given container shape or by forming a gas barrier coating on a base including a formed body formed beforehand in a given container shape. In the present description, a container fabricated by the former method may be referred to as a “joined container”, while a container fabricated by the latter method may be referred to as a “formed container”.
Examples of products, other than containers, which include a packaging material including a multilayer structure having gas barrier properties are container lids and vacuum insulators.
An example of a known multilayer structure with enhanced gas barrier properties is a multilayer structure including a transparent gas barrier coating containing a reaction product of alumina particles with a phosphorus compound (Patent Literature 1: WO 2011-122036 A1). This transparent gas barrier coating is formed by applying a coating liquid containing alumina particles and a phosphorus compound onto a base.